Heater



April 9, 1946. H. J. DE N. MccoLLuM 2,398,106

HEATER Filed June 5, 1945 2 Sheets-Sheet l Patented Apr. 9, 1946 HEATERHenry J. De N. McCollum, Chicago, Ill.; Thelmav McCollum executrix ofsaid Henry J. De N.

McCollum, deceased Application June 5, 1943, serial No. 489,765

(ci. 12s- 116) 10 Claims.

My invention relates to heaters and more particularly to heaters of theinternal combustion type commonly used to heat cabins or other enclosedspaces in aircraft, or for other similar purposes.

InA internal combustion heaters of the kind to which my inventionpertains, it is common to use electrical ignition means for igniting amixture of fuel and air supplied to the heater. Such electrical ignitionmeans is ordinarily energized from a battery or other outside source ofelectrical energy. In certain installations it is undesirable to connectthe heater with such an outside source of electrical energy and anobject of my invention is to provide an internal combustion heaterhaving an electrical ignition system which does not require an outsidesource of electrical energy. l

Another object of my invention is to provide an internal combustionheater wherein the same force which is utilized to force Ventilating airthrough the heater is also utilized to operate an Other objects andadvantages-will become apparent as the description proceeds.

In the drawings:

Fig. 1 is a longitudinal, vertical section through a heater embodying apreferred form of my invention;

Fig. 2 is a transverse, sectional View taken on the line 2-2 of Fig. l;I

Fig. 3 is a transverse, sectional view taken on the line 3-3 of Fig. 1;1

Fig. 4 is a partial, longitudinal section showing a modiiied form of myinvention in which I utilize a variable pitch fan for driving agenerator;

Fig. 5 is a side view partly in section showing a form of my inventionusing a variable pitch fan;

Fig. 6 is a longitudinal section through the variable pitch fan controlmechanism of the embodiments of Figs. 4 and 5; and l Fig. '7 is apartial, transverse section taken on the line 1-1 of Fig. 6.

'Ihe heater shown in Figs. 1 to 3 of the drawings comprises acylindrical casing I0 having a cated in the casing I0 and discharges hotproducts of combustionjnto the longitudinal passages I6 of a cylindricalheat exchanger indicated generally by reference numeral I8. Therighthand end of the heat exchanger I8 is closed by a plate 20 having acentral opening 22 in communication with an exhaust pipe 24 throughwhich the cooled products of combustion are discharged to atmosphere.

'I'he heat exchanger I8 has a corrugated shell 26 of stainless steel, orother suitable material, and i'lns 28 have their bases located in foldsin this shell 26, as best shown in Fig. 2. Those portions of the ns 218which project radially outward of the Vshell 26 are slotted as indicatedat 30 in Fig. l and project into the Ventilating air passage 32 formedbetween the shell 26 and casing I0 to transmitheat from the hot productsof combustion to this Ventilating air.

A muiller 34 is located in the heat exchanger I8 and comprises a sheetmetal cylinder 36 closed at its ends by sheet metal plates 38 and 40. Adisc 42 or heat insulating material is attached to the plate 38 toprotect this end of the muiller from the intense heat of the combustionchamber and the hot gases issuing therefrom. Partitions 44 divide themuiller into compartments which are lled with sound absorbing material,such as glass wool or stainless steel wool, and a row of openings 46forms acoustic couplings between each compartment and the gas passagesI6.

Part of the air which has passed over the ns 28 is diverted into thepipe 50 leading to a Venturi tube 52. A jet 54 discharges fuel, such asgasoline, into the throat of this Venturi tube, this jet being connectedto any suitable source ofv fuel supply by a pipe 56. The mixture of fueland air formed in the Venturi tube 52 is delivered to an induction pipe58, having a discharge end located in the combustion chamber I4 and sopositioned as to deliver the combustible mixture in a directiontangential to the circular wall of this combustion chamber. A housing 62attached to the combustion chamber provides a pocket 64 for a spark plug66 which serves to ignite the fuel and air mixture delivered to thecombustion chamber. This pocket connects with the interior of thecombustion chamber by way of an inlet opening 68 and an outlet opening10. A ring l2 serves to direct liquid fuel delivered to the combustionchamber into the pocket 64.

Current for the spark plug 66 is provided by a high tension alternator16 supported in a sheet metal frame 16, mounted in the forward end ofthe casing I4. A single wire connects the means. A high tension magnetowith a suitable circuit breaker could be used in lieu of the alternator,if desired.

When the heater is operating, the air entering the inlet or lefthand endofthe casing rotates propeller 22 and drives alternator 12 to create aspark across the gap between the terminals of the spark .plug 22 andthese sparks ignite and maintain combustion of the mixture of fuel andair delivered to the combustion chamber by the induction tube 52. Thehot products of combustion flow from the open or rlghthand end ,of thiscombustion chamber into the gas passages i2 and give up their heat tothe shell 28 and fins 422 of the heat exchanger i2. The cooled productsof combustion pass through the opening 22 in plate 20 and now throughexhaust pipe 24 to atmosphere.

The air supplied to the heater by the ram or blower absorbs some heatfrom the walls of the combustion chamber I4 and additional heat from theheat exchanger as this air flows lengthwise of the passage 22. Most ofthis heated air is utilized as Ventilating air to heat the airplanecabin or other space to be heated and passes from the tapered outlet end24 of the casing i0 either directly into the space to be heated or intoa duct system leading to selected outlet located in the same ordifferent spaces. to be heated.

A small portion of the heated air is diverted into Venturi tube 22 whereit mixes with fuel supplied by jet 52 to form a combustible mixture.This combustible mixture flows through induction tube 52 to thecombustion chamber where it is ignited by the spark plug 22. Thetangential arrangement of the outlet end 62 of the induction tube tendsto create a ring of flame in the combustion chamber and this ring offlame cooperates with the spark plug 22 in maintaining combustion.However, since the spark plug continues to operate as long as the heateris in operation, this spark plug alone is sufficient to maintaincontinuous combustion.

From the foregoing it will be apparent that I have provided a simple,inexpensive, light weight, compact and efficient heater which isentirely independent of any outside source of electrical energy tooperate its electrical ignition means. Such a heater may, therefore,belocated in places 4where no outside source of electrical energy isreadily available or where it would be disadvanable to have thispropeller and alternator operate continuously while the heater is inuse. In

certain installations, however, the slight resistance offered by thepropeller to air flow through the casing might be objectionable or itmight be desirable to discontinue alternator operation to preventmagnetic or other electrical interference or for other reasons it mightbe desirable to render the alternator inoperative as soon as the heaterhas attained normal operating conditions. In the modified structures ofFigs. 4 to '1, inclusive, I have shown means for automaticallydiscontinuing alternator operation as soon as the heater attains normaloperating temperature.

In Fig. 4, the alternator 12' is driven by a propeller 22' havingadjustable blades |00 which may be shifted from the operating positionshown in this figure to positions in planes passing through the axis ofthe propeller and alternator so that only the edges of the blades aredirectly exposed to the flow of Ventilating air through the casing.

tageous to provide wiring-to connect the heater Y with such an externalsource of current.

I wish particularly to point out that the alternator or other currentgenerator is so located that it is protected against the heat of thecombustion chamber and the gas passages leading therefrom, Furthermorethe propeller for operating this alternator is located in 'a contractedportion of the casing where the rate of air flow is relatively great andwhere the density of the air is a maximum because this air has not yetbeen exposed to the heat of the combustion chamber and heat exchanger.

In the embodiment of Figs. 1 to 3, inclusive, the propeller andalternator continue to operate as long as Ventilating air is supplied tothe inlet end of the heater casing. The propeller 22 offers littleresistance to the flow of air through the casing and for most purposesit is not objection'- In this form of my invention, the combustionchamber is provided with one or more re-igniters |02 to insuremaintenance of combustion in the heater after the alternator 12 hasceased to operate.

In the particular embodiment shown, the propeller blades |02 are pivotedin the propeller hub and are automatically shifted between operative andinoperative position in response to variations in heater temperature.When the heater is cold, the propeller blades assume the operativeposition shown, but after the heater has been started and reachesoperating temperature, these blades are automatically shifted toinoperative position wherein they cease to drive the alternator and odersubstantially no resistance to air flow through the heater casing. Sinceautomatically controlled fans of this general type are in commercial usefor other purposes, a relatively brief description of the operatingmechanism for such a propeller will sufllce.

As best shown in Figs. 6 and 7, each blade |02 may comprise a flattapered strip of sheet metal orother suitable material supported in ashaft |02 rotatably mounted in bearings provided by the propeller hub|22. Each shaft |04 carries a gear |22 meshing with the ring-like teethformed on the reduced extension iin of a piston ||2. The piston ||2 isslldably mounted in fluid-tight relationship in a cylindrical extension||4 of the propeller hub |26. The piston ||2 is urged to the right by aspring i|2 resting on a spring seat ||2 adiustably mounted in the coverplate |22 of the propeller hub |22. The spring seat ||2 has a wrenchreceiving portion |22 to facilitate adjustment of this spring seat tovary the tension of the spring ||2.

The propeller hub is mounted on the alternator shaft luto which it isattached by a set screw |22 or in any other suitable manner. This shafthas a reduced end |22 which extends through the piston ||2 and'itsextension ||2 and is slldably receivedin the-borev |22 of the springseat ||2. Ihe piston ||2 ispreferably provided with a pin |22 tollmitmovement of this piston under the force of spring vIll. This pin|22 serves to determinev the full operative position of the propellerblades |22.

VThe piston H2 is moved to the left by the expansion of fluid in a bulb|22, illustrated in Fig. 4 as being attached'tothe end wall of thecombustion chamber I2. A pipe |24 connects this bulb with a passage |22formed in a sleeve |22 which constitutes an extension of the housing ofthe alternator 10'. The passage |36 communicates with the annular groove|40 in the alternator shaft |24 and this groove in turn communicateswith a longitudinal passage |40 by way of drill hole |42. Theother endof `the passage |40 communicates with the interior of the cylinder I4through a cross bore |44 in the shaft |24.

When the heater is not operating, the uid in the bulb |32 is cool andcontracted so that the spring ||6 holds the piston ||2 and blades |00 inthe operative position shown in the drawings. If it is desired tooperateA the heater, Ventilating air is directed into the heater supplypipe |46 from a ram or any other suitable source of air supply androtates the propeller 82', thereby driving the alternator 16'.

This alternator supplies current to the spark plug 66 and ignitescombustible mixture delivered to the combustion chamber |4 through theinduction pipe 58. After the heater has been in operation a sufficientlylong time to attain normal operating temperature, the fluid in the bulb|32 heats up and expands and moves piston ||2 to the left, therebyshifting the propeller blades so that they lie in planes passing throughthe axis of the shaft |24. 'I'his renders the propeller inoperative andalso causes it to offer a minimum resistance to air flow through theheater. Thereafter combustion is maintained by the re-igniter |02. In

case ignition should fail in the heater for antr reason, the resultingcooling of the bulb |32 will permit spring ||6 to return the propellerblades to operative position, thereby driving the generator andre-starting the heater operation.

The modification shown in Fig. is the same as that of Fig. 4, except forthe position of the temperature responsive control bulb |32. In Fig. 4,this bulb is illustrated as being attached to a wall of the combustionchamber and responsive to the temperature of that chamber, whereas inFig. 5 the bulb |32 is placed in the duct |50 which conducts the heatedVentilating air to the space or spaces to be heated. A pipe |34 connectsthis bulb with the blade controlling mechanism so that the position ofthe propeller blades is dependent upon the temperature of theVentilating air in the duct |50. After the heater has been in operationa short time, the Ventilating air will be heated sufficiently to causethe propeller blades to assume their inoperative position and the a1-ternator 16 will remain idle as long as the heater continues to operatein a normal manner.

Except for the automatic mechanism for shifting the propeller blades,the modifications of Figs. 4 and 5 may be identical with that of Figs. 1to 3. The particular control mechanism for rendering the propellerblades operative or inoperative is to be considered as illustrativeonly, as any other suitable type of temperature responsive propeller maybe substituted for the one shown in the drawings. Some of the fans ofthis general type use stationary bimetallic blades which change theircurvature with variations in temperature. Similarly constructedpropellers could, be used in lieu of the type shown, but wherepropellers with bimetallic blades are used it would ordinarily bepreferable to place a propeller and alternator in the outlet duct|50which would have the disadvantage of subjecting the alternator tohigher temperatures and for most purposes the arrange ments shown inFigs. 4 and 5 would be preferable.

It is to be understood that my invention is not limited to theparticular details shown and described herein, but may assume numerousother forms. The combustion ch'amber, heat exchanger and muiiler shownherein are claimed in my co-pending applications. Serial Nos. 477,080,iiled February 25, 1943; 476,266, filed February 18, 1943; and 478,259,led March 6, 1943; and othertypes of combustion chambers, heatexchangers and muillers may be used in lieu of the particular ones shownherein.

I claim:

1. An internal combustion type of heater, comprising a combustionchamber, means for supplying a combustible mixture thereto, a heatexchanger receiving hot products of combustion from said combustionchamber, a casing surrounding said combustion chamber and heatexchanger, said casing having a tapered inlet adapted to be connected toa ram or blower, a propeller mounted in said tapered inlet, a hightension alternator driven by said propeller, and a spark plug suppliedwith current by said alternator and serving to ignite combustiblemixture in said combustion chamber.

2. A heater of the class described, comprising a combustion chamber,means for delivering a combutible mixture thereto, a spark plug forigniting said mixture, a heat exchanger receiving hot products ofcombustion from said combustion chamber, a cylindrical casing enclosingsaid combustion chamber and heat exchanger, said casing having an inletadapted to be connected to a source of air under pressure, electricalgenerating means located in said casing and connected to said sparkplug, and a propeller in said casing for drivingsaid generating means,said propeller being rotated by air ilow through' said casing.

3. A heater of the class described, comprising a combustion ch'amber, aheat exchanger receiving hot products of combustion from said combustionchamber, means for delivering a combustible mixture to said combustionchamber, a casing enclosing said combustion chamber and heat exchangerand having an inlet end for Ventilating air, an electrical igniter forsaid combustion chamber, and electrical generating means connected tosaid igniter, said electrical generating means being located in saidcasing ahead of said combustion chamber and heat exchanger, and apropeller for said generating means driven by air ilowing through saidcasing.

4. A heater of the class described, comprising a combustion chamber, aheat exchanger connected thereto, a casing enclosing said combustionchamber and heat exchanger and having an inlet end adapted to beconnected to a source of air under pressure, an electrical igniter forsaidA combustion chamber, an electrical generator for said igniter, anda motor located in said casing for driving said generator, said motorbeing operated by air flow through said casing.

5. A heater of the class described, comprising a combustion chamber, aheat exchanger connected thereto, a casing enclosing said combustionchamber and heat exchangerand having an inlet end adapted to beconnected to a source of air, an electrical igniter for said combustionchamber, a generator for supplying current to said igniter, an airdriven motor located in said casing for driving said generator, andmeans for rendering said motor inoperative when said heater is operatingnormally.

6. A heater of the class described, comprising a combustion chamber,means for supplying combustible mixture to said chamber, an electricalignited for said mixture, a generator for supplying current to saidigniter, a propeller for driving said generator. and means responsive totemperature variations of said combustion chamber for stopping theoperation o! said propeller and generator when the heater attains normaloperating temperature.

'7. A heater of the class described, comprising a combustion chamber,means for supplying combustible mixture thereto, an electrical igniterfor said combustion chamber, a generator for supplying current to saidigniter, a propeller responsive to the temperature of said h'eater, saidpropeller being connected to said generator for driving the same onlywhen current is needed to ignite said mixture, and temperature responsemeans responsive to the temperature of said combustion chamber forcontrolling the operation oi' said propeller.

8. A heater of the class described, comprising a. combustion chamber, aheat exchanger receiving hot gases from said combustion chamber, meansior circulating air over said heat exchanger, an igniter for saidcombustion chamber. a re-igniter for said combustion chamber, agenerator for supplying current to said igniter, an air operated meansfor driving said generator, said air operated means including automaticcontrol mechanism for rendering said means inoperative when said heaterattains normal operating temperatures.

9. A heater of the class described comprising a casing, a combustionchamber located in said casing, said casing having an inlet adapted tobe connected to means for directing air therethrough, a propeller drivenby airfilowing through said casing, ignition means for said combustionchamber operated by said propeller, and means for rendering saidpropeller inoperative when said combustion chamber reaches apredetermined temperature.

10. A heater of the class described, comprising a casing, a heatexchanger located in said casing, said casing having an inlet adapted tobe connectedA to a source of air supply. a combustion chamber forsupplying hot gases to said heat excxhanger, ignition means for saidcombustion chamber, a propeller operated by air ow through said casingfor operating said ignition means, and means for rendering saidpropeller inoperative when the air leaving said heat exchanger attai apredetermined temperature.

HENRY J. DE N. MecoLLUM.

